The team later specified that Betemit was diagnosed with a Grade 2-3 tear of the PCL ligament.
The 31-year-old Betemit, who was the Orioles' regular third baseman until the recall of Manny Machado last August, was on first base and running on the pitch when Machado flied to left. He collapsed near second base and was carted off the field.
When he reached the clubhouse, trainers put a leg brace on Betemit.
The team says he will be reevaluated on Tuesday.
Information from The Associated Press was used in this report.